@trishcnwma
What great ideas from everyone. The only thing I can add is to review the ER notes from your sister's recent ER visits. If you think they are accurate, tell them when checking in or see the triage nurse. Let them know about previous problems and ask them to review notes from xx/xx/xxxx visit. Or have a printed copy with you. Another alternative is a letter from her PCP that provides information on how she should be treated, appropriate medications, suggestions for multiple people to be with her to control her, etc...

There's no guarantee it will help or speed up the visit, but it might. Also, if you do not think the visit notes are accurate, every hospital has a policy for correcting medical records.